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Mon, 09 May 2022 20:20:03 -0700 (PDT) Received: from [192.168.1.100] ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id k4-20020a170902760400b0015ea9aabd19sm634142pll.241.2022.05.09.20.20.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 09 May 2022 20:20:02 -0700 (PDT) Message-ID: <61a2f9db-d150-a8e9-9d73-b01b34bf0989@kernel.dk> Date: Mon, 9 May 2022 21:20:01 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [PATCH 4/4] io_uring: implement multishot mode for accept Content-Language: en-US To: Hao Xu , io-uring@vger.kernel.org Cc: Pavel Begunkov References: <20220508153203.5544-1-haoxu.linux@gmail.com> From: Jens Axboe In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 5/8/22 9:32 AM, Hao Xu wrote: > From: Hao Xu > > Refactor io_accept() to support multishot mode. > > theoretical analysis: > 1) when connections come in fast > - singleshot: > add accept sqe(userpsace) --> accept inline userspace here too, like in the cover letter. > diff --git a/fs/io_uring.c b/fs/io_uring.c > index e0d12af04cd1..f21172913336 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -1146,6 +1146,7 @@ static const struct io_op_def io_op_defs[] = { > .unbound_nonreg_file = 1, > .pollin = 1, > .poll_exclusive = 1, > + .ioprio = 1, /* used for flags */ > }, > [IORING_OP_ASYNC_CANCEL] = { > .audit_skip = 1, > @@ -5706,6 +5707,7 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags) > static int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) > { > struct io_accept *accept = &req->accept; > + unsigned flags; > > if (sqe->len || sqe->buf_index) > return -EINVAL; > @@ -5714,19 +5716,26 @@ static int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) > accept->addr_len = u64_to_user_ptr(READ_ONCE(sqe->addr2)); > accept->flags = READ_ONCE(sqe->accept_flags); > accept->nofile = rlimit(RLIMIT_NOFILE); > + flags = READ_ONCE(sqe->ioprio); > + if (flags & ~IORING_ACCEPT_MULTISHOT) > + return -EINVAL; > > accept->file_slot = READ_ONCE(sqe->file_index); > - if (accept->file_slot && (accept->flags & SOCK_CLOEXEC)) > + if (accept->file_slot && ((accept->flags & SOCK_CLOEXEC) || > + flags & IORING_ACCEPT_MULTISHOT)) > return -EINVAL; So something ala: if (accept_>file_slot) { if (accept->flags & SOCK_CLOEXEC) return -EINVAL; if (flags & IORING_ACCEPT_MULTISHOT && accept->file_slot != IORING_FILE_INDEX_ALLOC) return -EINVAL; } when rebased as mentioned in the cover reply. if (accept->file_slot && (accept->flags & SOCK_CLOEXEC)) > static int io_accept(struct io_kiocb *req, unsigned int issue_flags) > { > + struct io_ring_ctx *ctx = req->ctx; > struct io_accept *accept = &req->accept; > bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK; > unsigned int file_flags = force_nonblock ? O_NONBLOCK : 0; > @@ -5734,6 +5743,7 @@ static int io_accept(struct io_kiocb *req, unsigned int issue_flags) > struct file *file; > int ret, fd; > > +retry: > if (!fixed) { > fd = __get_unused_fd_flags(accept->flags, accept->nofile); > if (unlikely(fd < 0)) > @@ -5745,8 +5755,12 @@ static int io_accept(struct io_kiocb *req, unsigned int issue_flags) > if (!fixed) > put_unused_fd(fd); > ret = PTR_ERR(file); > - if (ret == -EAGAIN && force_nonblock) > - return -EAGAIN; > + if (ret == -EAGAIN && force_nonblock) { > + if ((req->flags & IO_APOLL_MULTI_POLLED) == > + IO_APOLL_MULTI_POLLED) > + ret = 0; > + return ret; > + } Could probably do with a comment here for this check, it's not immediately obvious unless you've already been deep in this part. > @@ -5757,8 +5771,26 @@ static int io_accept(struct io_kiocb *req, unsigned int issue_flags) > ret = io_install_fixed_file(req, file, issue_flags, > accept->file_slot - 1); > } > - __io_req_complete(req, issue_flags, ret, 0); > - return 0; > + > + if (!(req->flags & REQ_F_APOLL_MULTISHOT)) { > + __io_req_complete(req, issue_flags, ret, 0); > + return 0; > + } > + if (ret >= 0) { > + bool filled; > + > + spin_lock(&ctx->completion_lock); > + filled = io_fill_cqe_aux(ctx, req->cqe.user_data, ret, > + IORING_CQE_F_MORE); > + io_commit_cqring(ctx); > + spin_unlock(&ctx->completion_lock); > + if (!filled) > + return -ECANCELED; > + io_cqring_ev_posted(ctx); > + goto retry; > + } > + > + return ret; > } As mentioned, I still think this should be: ... if (filled) { io_cqring_ev_posted(ctx); goto retry; } ret = -ECANCELED; } return ret; -- Jens Axboe